The present inventin relates to a driving mechanism, and more particularly to a filter driving mechanism for a color optical reader or scanner.
The conventional filter driving mechanism for a color optical reader, as shown in FIG. 1, includes a filter frame 1, two side belt wheels 6, 7 and a transmitting belt 8 which is connected to a first connecting portion 4a of frame 1, wound around wheel 6, extended through guiding members 5c, 5b, and 5a of frame 1, wound around wheel 7 and connected to a second connecting portion 4b of frame 1 so that belt 8 can move frame 1 in the desired direction.
The filter is brought into scanning positin by belt 8 which, however, is elastic, has poor rigidity and a large inertia so that the scanning position for filter frame 1 always tends to produce a deviation. In addition, belt 8 is relatively easily fatigued owing to its frequent use and has a shortened life-span if it is excessively tightened. Furthermore, belt 8 is loosely guided by guiding members 5a-5c of filter frame 1 so that filter frame 1 cannot be moved steadily and positively guided since belt 8 has a variable elasticity.